Process for producing polyester fibers and having high and constant shrinkage

ABSTRACT

POLYESTER FIBERS OR FILAMENTS WHICH EXHIBIT A HIGH AND CONSTANT SHRINKAGE AT VARYING HEAT-TREATMENT TEMPERATURES FOR DEVELOPING OF SHRINKAGE ARE OBTAINED BY DRAWING UNDRAWN FIBERS OR FILAMENTS TO AT LEAST 3 TIMES THEIR ORIGINAL LENGTH AT A TEMPERATURE OF 40 TO 70*C., SHRINKING THE DRAWN FIBERS OR FILAMENTS AT A TEMPERATURE OF 65-130* C. BY 10-50% OF THE DRAWN LENGTH, AND THEREAFTER, DRAWING THE FIBERS OR FILAMENTS BY 10-80% OF THE SHRUNKEN LENGTH AT A TEMPERATURE OF 40-70*C. AND TO AN EXTENT NOT IN EXCESS OF 1.2 TIMES THE ABOVE-MENTIONED DRAWN LENGTH. SPUN YARNS AND TEXTILE FABRICS CONTAINING THE SO OBTAINED FIBERS OR FILAMENTS HAVE A HIGH AND UNIFORM SHRINKAGE AT VARYING HEAT-TREATMENT TEMPERATURES.

y 27, 1971 TAKESHI KONISHI E L 3,595,953

PROCESS FOR PRODUCING POLYESTER FIBERS AND HAVING HIGH AND CONSTANT SHRINKAGE Filed May 14, 1969 SHRINKAGE I I I 1 80 I00 I20 I40 I60|8020022024026O TEMPERATURE (C) United States Patent 3,595,953 PROCESS FUR PRODUCING POLYESTER FIBERS AND HAVING HIGH AND CONSTANT SHRINKAGE Takeshi Konishi, Kurashiki, and Keizo Ueda, Nishinomiya, Japan, assignors to Kurashiki Rayon Co., Ltd., Kurashiki, Okayama Prefecture, Japan Filed May 14, 1969, Ser. No. 824,604 Claims priority, application .iapan, May 17, 1968, 43/33,337; May 22, 1968, 43/3 1,537; May 25, 1968, 43/395,642

lint. Cl. D02j 1/22 US. Cl. 264-290 6 Claims ABSTRACT OF THE DISCLOSURE Polyester fibers or filaments which exhibit a high and constant shrinkage at varying heat-treatment temperatures for development of shrinkage are obtained by drawing undrawn fibers or filaments to a least 3 times their original length at a temperature of 40 to 70 C., shrinking the drawn fibers or filaments at a temperature of 65l30 C. by 10-50% of the drawn length, and thereafter, drawing the fibers or filaments by 10-80% of the shrunken length at a temperature of 40-70" C. and to an extent not in excess of 1.2 times the above-mentioned drawn length. Spun yarns and textile fabrics containing the so obtained fibers or filaments have a high and uniform shrinkage at varying heat-treatment temperatures.

This invention relates to polyester fibers or filaments which exhibit a high and constant percent shrinkage at varying heat-treatment temperatures for development of shrinkage.

One of the conventional methods of obtaining polyester synthetic fibers showing high percent shrinkage involves wetting an undrawn polyethylene terephthalate fiber or filament having a birefringence of 4-ll 10 with a non-solvent containing a hydroxyl group, drawing it at 35- 50" C. to at least 90% of the breaking limit of draw ratio to form a highly shrinkable fiber or filament, and thereafter heat-treating it under relaxation at a temperature in the range of 90 to 200 C. to develop crimps. Another method involves drawing an undrawn fiber or filament of a polyester consisting predominantly of polyethylene terephthalate to 2.3-2.6 times at 65-100" C. to form a highly shrinkable fiber or filament, subjecting it to a tension of 0.1 to 0.93 g./d., and heat-treating it under relaxation at 95-180 C. to develop crimps.

Highly shrunken polyester fibers or filaments obtained by such conventional methods, however, change in their shrinkage according to variations in heat-treating temperature for development of shrinkage, and so the resulting shrunken yarn undergoes irregularities in shrinkage, exhibiting a reduced commercial value.

We have found that polyester fibers or filaments which exhibit a high and constant shrinkage at varying heattreatment temperatures for development of shrinkage are obtained by drawing undrawn fibers or filaments ice to at least 3 times their original length at a temperature of 40 to 70 C. (a first drawing step), shrinking the drawn fibers or filaments at a temperature of 130 C. by 10-50% of the drawn length (a shrinking step), and thereafter, drawing the fibers or filaments by 10-80% of the shrunken length at a temperature in the range of 40- C. and to an extent not in excess of 1.2 times the abovementioned drawn length (a second drawing step); a spun yarn obtained by mix-spinning the so obtained highly shrinkable polyester fibers or filaments and a non-shrinkable fiber or filament has a very uniform and high bulk even when there are changes in heat-treatment temperature for development of bulk; and that a textile fabric produced by using such spun yarn, even when heat-treatment temperatures for the development of bulk change, exhibits a very uniform and high bulk, and has excellent tactile hand and pilling resistance.

An object of the present invention is to provide a novel process for producing polyester fibers and filaments which have a very uniform and high shrinkage even when there are changes in heat-treatment temperature for the development of shrinkage.

Another object of the invention is to provide a novel spun yarn which exhibits a very uniform and high bulk even when there are changes in heat-treatment temperature for the development of bulk.

Still another object of the invention is to provide a novel textile fabric which exhibits a very uniform and high bulk and has excellent tactile hand and pilling resistance even when there are changes in heat-treatment temperature for the development of bulk.

Many other objects and advantages of the invention will become apparent from the following description.

The polyesters used in this invention include homopolymers and copolymers containing at least mole percent, preferably at least mole percent of ethylene terephthalate recurring units and homopolymers and c0- polymers containing at least 85 mole percent, preferably at least 90 mole percent of p-B-oxyethoxybenzoic acid recurring units. These copolymers may contain as a third component 0-15 mole percent, preferably 0-10 mole percent of a known dicarboxylic acid component such as ethylene isophthalate and ethylene adipate and 0-15 mole percent, preferably 0-10 mole percent of a known alcohol component such as methoxy polyethylene glycol, pentaerythritol and diethylene glycol.

The first drawing step according to the invention comprises drawing an undrawn fiber or filament of polyester at a temperature of 40-70 C., preferably 55-67" C. to at least 3 times, preferably at least 3.2 times, the original length. At a temperature below 40 C., many single filaments tend to be broken and wound around rollers, thus making the drawing difiicult or impossible. On the other hand, when the drawing temperature is in excess of 70 C., it is difiicult for the drawn fiber or filament to exhibit a sufiicient shrinkage in the subsequent shrinking step, and therefore, a highly shrunken yarn cannot be obtained. Preferable drawing temperatures for avoiding the foregoing disadvantages range from 55 to 67 C. If the draw ratio does not exceed 3, a filament or fiber obtained by shrinking the resulting highly shrinkable yarn lacks stiffness. A preferable draw ratio is at least 3.2.

The subsequent shrinking step comprises shrinking the drawn fiber or filament obtained in the first drawing step by -50%, preferably 40%, of the drawn length at a temperature in the range of 65 to 130 C., preferably 80130 C. and in excess of the drawing temperature. The heating temperatures below 65 C. are not desirable as the fiber or filament does not show sufficient shrinkage at this temperature and a highly shrunken fiber or filament cannot be obtained. Suflicient shrinkage requires temperatures of at least 80 C. When the temperature exceeds 130 0, there can be obtained a fiber or filament having a high shrinkage, but the resulting fiber is somewhat inferior in properties or sticks onto rollers as compared with those obtained at the heating temperatures below 130 C. In other words, at temperatures below 130 C., the fiber or filament exhibits almost the same shrinkage over a wider range of heat-treatment temperatures for the development of shrinkage. It is essential that the shirnkage should be effected at a temperature in excess of the temperature of the first drawing step. Otherwise, the treated fiber or filament hardly shrinks, and subsequent treatments would become difficult or impossible. Preferably, this difference is at least 2 C.

If the percent shrinkage does not exceed 10% of the drawn length, a sulficient drawing in the second drawing step cannot be expected, and therefore, it is impossible to obtain a fiber having a high shrinkage. On the other hand, a shrinkage exceeding 50% is undesirable as it often causes filaments to stick in a shrinking step. The ratio of shrinkage in the shrinking step should preferably be not less than 20% but not more than The subsequent second drawing step comprises drawing the fiber or filament obtained in the shrinking step to not more than 1.2 times, preferably not more than 1.1 times, the length drawn in the first drawing step at a temperature in the range of 40 to 70 C., preferably 65 C. and by 1080%, preferably 20-45% of the shrunken length of the fiber or filament obtained in the shrinking step.

If the drawing temperature exceeds C., it is impossible to obtain a fiber or filament having a sufiicient shrinkage. If it is below 40 C., fuzzes occur during the drawing, and the drawing step often becomes unstable. To avoid disadvantages, temperatures of not less than 50 C. but not more than 65 C. are of especial preference.

When the draw ratio in the second drawing step does not exceed 10% of the hot shrunken length of the fiber or filament, the resulting fiber or filament does not show shrinkage. The draw ratio in excess of however, is not desirable as it causes the occurrence of fuzzes during the drawing operation. To avoid these disadvantages, it is desirable to effect the second step drawing by 20-45% of the hot shrunken length of the fiber or filament.

In addition to this requirement, it is also essential in the second drawing step to draw the fiber or filament to not more than 1.2 times the drawn length of the fiber of filament obtained in the first drawing step. If the length of the fiber or filament obtained in the second drawing step is in excess of 1.2 times that of the fiber of filament obtained in the first drawing step, fuzzes occur during the second drawing step while a fiber or filament having a high shrinkage can be obtained. In addition, the shrinkage differs with changes in heattreatment temperatures for the development of shrinkage. Hence, it is impossible to achieve the objects of the present invention. To overcome these difficulties, it is preferable to abjust the drawn length of the fiber or filament obtained in this second drawing step to not more than 1.1 times the length obtained in the first drawing step.

Usually, the first drawing, shrinking, and second drawing steps should be preferably be effected continuously. Even if they are effected intermittently, however, no particular difiiculty arises. In the continuous treatment, it sometimes happens that a fiber or filament shrunken in the shrinking step enters the second drawing step while it is not sulficiently cooled, and for this reason, it is drawn at a temperature higher than the drawing temperature of the second drawing step as specified. It is necessary therefore to cool the fiber or filament; for instance, by showering cold water between the shrinking step and the second drawing step.

As a heat transfer medium usable in the first drawing step, shrinking step and second drawing step, we can mention water, steam, air or a hot plate. In the shrinking step, a liquid inert to polyester fibers or filaments, such as water, should preferably be used. When a gaseous bath such as air bath is used in the shrinking step, a sulficient shrinking cannot be achieved as a sufficient heat transfer is not effected. A water bath is most preferable to shrink a thick tow.

According to the process of the invention, there can be obtained polyester fibers or filaments having high shrinkage which exhibit a very uniform shrinkage even when heat-treatment temperatures for the development of shrinkage vary. The properties of the obtained fibers or filaments can be further improved if an undrawn fiber or filament of polyester is heated to 30 to 70 C. prior to the first drawing step (see Examples 4 and 5).

In the heat-treatment of the shrunken yarn obtained by the present invention, a higher shrinkage is obtained when the yarn is rapidly heated than when it is gradually heated. For instance, a shrinkage attained when a fiber or filament having a high shrinkability is rapidly immersed in a water bath at 98 C. is larger than one attained when it is immersed in water at room temperature and gradually heated up to 98 C.

A method is known in which treating conditions similar to those of the present invention are employed (see U.S. Pat. 3,107,140 and the corresponding French Pat. 1,297,521). U.S. Pat. 3,107,140 discloses a process for the production of fibers or filaments of polyethylene terephthalate having an improved dyeability, an adjustable shrinkage in boiling water and an adjustable thermoshrinkage which comprises drawing fibers or filaments of polyethylene terephthalate to several time (44.5 times) the original length, shrinking said fibers or filaments by 8- 40% (12-30%) at a temperature of at least C. (233250 C.), and then stretching the fibers or filaments a second time by 3% to at most the breaking limit of said fibers or filaments. The U.S. patent is similar to the present invention in that it comprises a first drawing step, a shrinking step and a second drawing step. But they differ from each other in respect of the first drawing temperature and the shrinking temperature. As will be seen from the examples appearing hereinbelow, a yarn having uniform and high shrinkage cannot be obtained if any one if the treating conditions according to the present invention is not fulfilled. It is obvious therefore that a yarn having uniform and high shrinkage intended by the present invention cannot be obtained by the process of the U.S. patent.

According to the process of the present invention, a polyester fiber or filament having a certain high shrinkage can be obtained even when it is treated at a temperature over a wide range. We have further gone into the research work, and found that when the process of the present invention is applied to an undrawn polyester filament having latent crimps, coil-like crimps which are uniform and rich in bulk can be obtained. When a composite fiber or filament consisting mainly of polyester or an undrawn yarn having latent crimps which has been cooled asymmetrically at the time of spinning is drawn, shrunken and again drawn in accordance with the conditions of the present invention, coily crimps more excellent than those obtained under ordinary drawing conditions can be obtained. In addition, even when the heat-treatment temperatures for the development of the crimps are varied,

the state of crimps remains almost constant. Therefore, the process of the present invention is also applicable to such composite fiber and latently crimpable yarn.

,When a spun yarn obtained by mix-spinning the shrinkable polyester fiber obtained in accordance with the process of the invention with a non-shrinkable fiber in a customary manner is heat-treated, there can be obtained a uniform and high bulk even when the heat-treatment temperatures for the development of bulk are varied. Therefore, the spun yarn obtained by mix-spinning the shrinkable polyester fiber obtained according to the process of the invention and a non-shrinkable fiber, and the resulting bulky yarn are also within the scope of the Present invention.

Furthermore, when a textile fabric obtained in a customary manner by using the spun yarn according to the present invention is heat-treated, there can be obtained a textile fabric having uniform and high bulk even when the heat-treatment temperatures for the development of bulk are varied, and also having excellent tactile hand and resistance to pilling. Therefore, such textile fabric and the resulting bulky textile fabric are also within the scope of the present invention.

The invention will be more specifically described with reference to the following non-limitative examples. The intrinsic viscosities described in the examples were meas ured in a mixed solvent of tetrachloroethane and phenol in equal amounts at 30 C.

EXAMPLE 1 An undrawn yarn (140,000 denier/14,000 filaments) of a polyester consisting of 95 mole percent of ethylene terephthalate units and 5 mole percent of ethylene isophthalate units which had an intrinsic viscosity of 0.62 and a birefringence of 0.003 was fed to a first roller at a rate of 20 m./min., conducted to a water bath (first bath) at 60 C., and passed through a second roller at a rate of 65 m./min. The undrawn yarn was drawn to 3.25 times the original length in the first bath. The tow which had left the second roller was conducted to a water bath at 98 C. (second bath), and then passed through a third roller at a rate of 45.5 m./min. The tow was shrunken in the second bath by 30% of the drawn length. The tow was further led to a water bath maintained at 55 C. (third bath), and then passed througha fourth roller at a rate of 65.5 m./min. The tow was drawn in the third bath by 45% of the shrunken length (to 1.45 times the shrunken length). The first to fourth rollers each consisted of 5 to 9 rollers to prevent slippage of the tow on the rollers.

The treating conditions for the tow which had passed successively through the first roller, first bath, second roller, second bath, third roller, third bath, and fourth roller are shown in Table I below.

The so treated tow was oiled, crimped, dried, and cut into staple fibers.

The obtained staple fiber had an S (the percent shrinkage of the staple fiber in boiling water as against that before immersion in boiling water) was 20.5%, and had an S (the percent shrinkage of the staple fiber immersed in boiling water and heated to 130 C. under pressure as against the original length) of 20.7%. Hence, AS (the difference between S and S was 0.2%. These values are shown in Table II.

It is seen that despite the fact that the staple fibers obtained by the present example (the highly shrinkable yarn as referred to in the present invention means a yarn having an S above about 7%) have a high S there is almost no difference in shrinkage between a case of treating them with boiling water and a case of treating them with water at 130 C.

A blend of 40% of the so obtained staple fibers and 60% of polyethylene terephthalate staple fibers, having an S and an S of almost Zero was spun to make a 180 denier spun yarn. This spun yarn exhibited quite the same bulkiness on treatment in boiling water and in water at 130 C. This can also be seen from the fact that this spun yarn has an S of 19.5%, an S of 19.6% and AS of 0.1%, and that generally, the higher is the shrinkage of a spun yarn is, the higher the bulkiness is after shrinking treatment.

A textile fabric was prepared by using the spun yarn obtained above. When the fabric was subjected to steam at 100 C., the fabric had a very uniform and excellent tactile hand, and resistance to pilling.

EXAMPLE 2 An undrawn fiber or filament of a copolyester consisting of 100 moles of ethylene terephthalate units, 0.3 mole of methoxy polyethylene glycol having a molecular weight of 1500, 0.07 mole of pentaerythritol, and 4.2 moles of diethylene glycol was drawn, shrunken, and drawn again in accordance with the conditions described in Table I to get a staple fiber.

Using the staple fibers, a spun yarn was produced in the same manner as in Example 1. The obtained spun yarn had an S of 15.1% and AS of 0.1%.

EXAMPLES 3-5 Using an undrawn fiber or filament of a polyester consisting of 91 mole percent of ethylene terephthalate and 9 mole percent of ethylene adipate and having an intrinsic viscosity of 0.50 and a birefringence of 0.0015 (Example 3), a polyester consisting of 100 mole percent of ethylene terephthalate and 4.0 mole percent of diethylene glycol and having an intrinsic viscosity of 0.58 and a birefringence of 0.002 which had been pretreated with hot water shower at 59 C. (Example 4), and the same copolyester as used in Example 4 which had not been pre-treated (Example 5), a staple fiber was obtained in accordance with the treating conditions given in Table I, Table II shows the S and AS of each of the staple fibers obtained.

Comparative Example 1 A staple fiber was produced from the same undrawn fiber or filament as used in Example 1 in the same manner as in Example 1 except that it was drawn in the first drawing step to 3.4 times at C. The obtained staple fiber had AS of 5.5%.

A spun yarn prepared from this staple fiber in the same manner as in Example 1 had an S of 18.0% with AS of 5.2%. It was confirmed at first sight that the bulkiness of the spun yarn shrunken in boiling water was evidently inferior to that of the yarn treated in water at C.

As will be seen from Table II, the obtained staple fiber had an S of 18.5% and AS of 5.5%. Hence, there is a larger difference between the shrinkage at 100 C. and that at 130 C. than the staple fiber according to the present invention. It will be seen that if any one of the treating conditions of the present invention is not fulfilled, it is impossible to obtain a staple fiber having a uniform shrinkage over a wide range of temperatures.

Comparative Examples 2l4 In each example, a staple fiber was obtained in accordance with the procedure of Example 1 except using an undrawn fiber or filament described in Table I and the treating conditions given in Table I. The S and AS of each of the obtained staple fibers are shown in Table II. It is seen from Table II that unless the procedure of the present invention is followed, it is impossible to obtain a staple fiber having a uniform shrinkage at temperatures in a wide range, and at times, the treating procedure be comes bad.

Tabl e I Treating condi tion Example;

Compra ya Speed f 2nd. roller Shrinkage of subsequent treatsubsequent treat- TABLE II Remarks Exnmplo Comp. Example Somewhat frequent winding around the Second roller, and working eflleieneies somewhat lowered.

Breakage of monoliluinents and drawing impossible with the filaments wound around second roller.

May fuzzes occurred in the 4th roller.

The filaments hardly shrunken in the second bath, and the subsequent; treatments impossible.

l0 Monofilanients broken on the 4th roller.

Drawing condition had.

of 5rd roller be tenpegacure up a after 5rd roller, and again fed into s the 1st draws the of the let draw- EXAMPLE 6 An undrawn yarn (140,000 denier/ 14,000 filaments) of polyethylene terephthalate having an intrinsic viscosity of 0.62 and a birefringence of 0.003 was passed through a first roller at a rate of 20 m./min., conducted to a water bath (first bath) at 62 C., and passed through a second roller at a rate of 74 m./min. In the first bath, the yarn was drawn to 3.7 times. The tow which had left the second rollers were conducted to a water bath (second bath) with a length of 3 meters maintained at 96 C., and withdrawn with a third roller at a rate of 52 m./rnin. In the second bath, the tow was shrunken by 30%, and then conducted to a water bath (third bath) at 52 C. via the third roller. It was then withdrawn with a fourth roller at a rate of 68 m./min. In the third bath, the tow was drawn by 31%. The tow was cooled with water at 20 C. between the second and third baths.

Each of the first to fourth rollers consisted of 5-7 rollers to prevent slippage of the tow on the surfaces of the rollers.

The dry heat shrinkage curve of the fiber contained in this example is indicated as (A) in the drawing.

In the meantime, the same undrawn polyethylene terephthalate yarn as mentioned above was drawn in the first drawing step to 3.7 times the original length in a water bath at 50 C. or 95 C. with the other conditions being the same as above mentioned. The dry heat shrinkage curve of each of the fibers obtained in this manner is indicated as (B) and (C) respectively in the drawing.

The dry heat shrinkage curve used here is determined as follows:

Filaments having a total denier of about 50 are associated in parallel to each other, and subjected to a load of 0.1 g. so that the obtained bundle will not slacken to thereby adjust the bundle length to cm. It is then suspended from a graduated metal plate. The metal plate from which the yarn is suspended is placed into a test tube. The test tube is immersed in an oil bath, and heated from room temperature to about 250 C. over a period of about 30 minutes. The temperature within the test tube and the shrinkage of the yarn during the temperature raising are plotted.

It is seen from the drawings that the fibers or filaments according to the present invention are shrunken highly by heat and that the shrinkage is almost the same even if the heat-treatment temperature for the development of the shrinkage varies, for instance, from 140 C. to 220 C. in the case of (A). On the other hand, the drawing indicates that the polyester fibers or filaments obtained by the treating conditions outside the scope of the present invention do not exhibit a uniform shrinkage, as shown in (B) and (C).

The obtained yarn was mechanically crimped on application of an oil preparation, dried in a warm air at 60 C., and cut to a length of 51 mm. A blend of 50% of the so obtained staple fibers (abbreviated as S yarn) and 50% of 2.8 denier staple fibers of polyethylene terephthalate which hardly shrank in a hot air at 180 C. was spun to make a spun yarn of 22 cotton count and a twist of 13 turns per 25.4 mm. When the spun yarn was heated in hot air at 140 C., the S yarn in the spun yarn exhibited ,a shrinkage of about 15%, and the spun yarn became ,bulky and exhibited a good tactile hand. When it Was heated with steam at 120 C. (corresponding to 160 C. in hot air) or with hot air at 170 C., the S yarn exhibited almost the same shrinkage, and the spun yarns exhibited almost the same bulkiness in both cases. The bulkiness was very uniform along the length of the yarns.

We claim:

1. A process for the preparation of a highly shrinkable polyester fiber or filament having a uniform shrinkage which comprises 1) drawing an undrawn fiber or filament of a polyester in a first drawing step to at least 3 times the original length at a temperature in the range from 40 to 70 C.; (2) thereafter shrinking the drawn fiber of filament in a shrinking step by 10-50% of the drawn length at a temperature in the range from '65 to 130 C. and in excess of the first drawing temperature; and (3) subsequently drawing the shrunken fiber or filament in a second drawing step to not more than 1.2 times the length obtained in the first drawing step and by 10-80% of the shrunken length at a temperature in the range of 40-70 C.

2. The process of claim 1 wherein the first drawing step is effected by drawing the undrawn fiber or filament to at least 3.2 times the original length at a temperature in the range of -67 C., the shrinking step is eifected by shrinking the drawn fiber or filament by 20-40% of the drawn length at a temperature of -130 C., and

the second drawing step is effected by drawing the shrunken fiber or filament to not more than 1.1 times the length obtained in the first drawing step and by 20-45% of the shrunken length at a temperature in the range of 50-65 C.

3. The process of claim 1 wherein said undrawn polyester fiber or filament is pre-heated to 30-70 C.

4. The process of claim 1 wherein said undrawn fiber or filament is one consisting of a polymer containing at least mole percent of ethylene terephthalate recurring units.

5. The process of claim 1 wherein the said undrawn polyester fiber or filament contains at least 85 mole percent of ethylene terephthalate recurring units and 0-15 mole percent of a dicarboxylic acid component selected from ethylene isophthalate and ethylene adipate and 0-15 mole percent of an alcohol component selected from methoxy polyethylene glycol, pentaerythritol and diethylene glycol.

6. The process of claim 1 wherein the temperature of the shrinking step is at least 2 C. higher than the temperature in the first drawing step.

References Cited UNITED STATES PATENTS 3,107,140 10/1963 Kurzke et al. 264290 FOREIGN PATENTS 903,914 12/1966 Great Britain 264290 1,012,461 12/1965 Great Britain 264290 1,050,393 8/1962 Great Britain 264-290 JULIUS FROME, Primary Examiner H. MINTZ, Assistant Examiner US. Cl. X.R. 264-235, 342 

